Im running a hosting company right now but I want to change my domain, how do I go abouts doing this so it doesnt affect anything
well.. If you setup a new domain name, you'll need to change the name servers so that will be anywhere from 20min - 3 days down. Usually it's quick though. then you could setup your site files on the new domain and redirect all traffic from your old to your new one. If you need to xfer customers to the new server too, which should be dealt with delicately. you'll want to change the A Name records for a mass change.
And don't forget to change your TTL (Time to Live). That is critical when it comes to switching providers. Especially, if you don't want any down time at all.